Sun machines' ``boot net'' feature deals with bootp (or also DHCP in newer machines) to get an IP address, etc. It then can parse that information, possibly in combination with responses from a bootparam server, to boot anything you want. It even downloads the initial kernel from the server.

I'm not sure what a "bootparam server" is, but everything else you've said there applies to PXE too. You don't have to burn a special ROM, that's the whole point: PXE is a generic client "boot ROM" that can boot anything. Of course, only motherboards with onboard Ethernet tend to come with PXE -- if your network card is a, er, card, then you'd need to blow a ROM for it anyway.

In an unscientific sample size of 2, it seems that all recent motherboards with built-in Ethernet (Spacewalker Athlon thing and Supermicro 370DE6, i.e. pretty much opposite ends of the spectrum) also support PXE.

Peter